France has been stunned by the fate of la petite Typhaine, a little girl lost in a disturbing saga of parental brutality, brazen lies and the failings of the social safeguards which are meant to protect children.

The case, which bears striking similarities to the death of Baby P and the false abduction of Shannon Matthews, revolves around Typhaine, a five-year- old with a cheeky round face. She was reported to have been abducted from under her mother's nose on 14 June. According to her mother, Anne-Sophie Faucheur, 24, the little girl "vanished in the space of a second" as she ran a few yards ahead of her on the streets of Maubeuge, a depressed industrial town in northern France.

When the investigation made no progress, Ms Faucheur gave a tearful press conference in which she accused the police of feet-dragging and incompetence. "One thing is sure," she said, sobbing in front of the TV cameras. "We will get her back. We miss her so much. She is in our hearts always."

Sitting beside her, nodding in sympathy, was her partner, Nicolas Willot, Typhaine's stepfather, who is also 24.

This week, almost six months later, Willot, a hospital porter and voluntary fireman, led French and Belgian police to Typhaine's shallow grave in woodland in south central Belgium, 50 miles from their home. A few days earlier he told French investigators that Typhaine had died after she was hurled naked into a cold shower by her mother. This was, he said, a punishment for wetting the bed – a punishment that "went wrong".

Ms Faucheur at first insisted that there had been an "accident in the shower". She later confessed that her partner's version was correct.

The case is one of a series in recent years involving child abuse or extreme neglect amongst poor white French families, especially in the depressed ex-industrial towns of northern France. The case has also revived disturbing memories for the people of Belgium. The body of little Typhaine was found close to the village of Marcinelle, once the home of the convicted child murderer, Marc Dutroux.

Mr Willot told police the girl had frequently been "tortured" by her mother and that she had become the "whipping child of the family" (which included an older sister and a baby half-sister).

If so, Typhaine's martyrdom had not lasted long. One of the most disturbing facts of the case is that Ms Faucheur had herself kidnapped her daughter from outside a kindergarten in Lille only five months before. Until then, the little girl had been living with her paternal grandmother and her natural father, François Taton.

No attempt was made by the French legal system or social services or Mr Taton himself to reclaim the child. When Ms Faucheur and Mr Taton separated four years earlier, they had agreed informally to take one daughter each. Typhaine had gone with her father and her mother is said to have hardly known her before turning up at the school gates in Lille.

Ms Faucheur abducted the child by telling teachers that Typhaine's father was ill and could not come to collect her. Awkward questions are now being asked about why nothing was done to challenge Ms Faucheur's action, or at least investigate Typhaine's well-being in her new home. Raphael Théry, a lawyer representing Typhaine's father, said that his client had decided to accept the situation because "he placed his confidence in the mother. If a mother comes to claim her child, you imagine it is to give her affection and love".

It is now believed that Typhaine had been dead for four days before her disappearance was reported to police. Her body was kept for at least two days in the cellar of the family house at Aulnoye-Aymeries, near Maubeuge.

While Typhaine's body still lay in the cellar, her mother invited friends and family to a restaurant to celebrate the christening of her baby daughter. When they asked why Typhaine was not there, Ms Faucheur said that the little girl had been left at home to watch videos in case her natural father "took advantage of the party" to steal her back.

Willot explained to police that he had loaded the dead child into his van when he set out on one of his frequent trips across the border to Belgium to buy cheaper petrol. His choice of a burial place near the village once inhabited by Marc Dutroux, convicted in 2004 for multiple child murders, is believed to be a macabre coincidence.

The websites of French newspapers have been flooded with messages expressing shock at the "cold-blooded cheek" of the child's mother, who "made us all believe in her suffering". But many messages also query the legal and social welfare systems' failure to see the danger signs. The same questions are being asked by investigators and local politicians.

"It is easy to be wise after the event but there was a disturbing pattern," said one politician, who asked not be named. "Apart from the unchallenged abduction by her mother, there was the fact that Typhaine did not go to school and was rarely seen outside the house."

Even now, investigators are not convinced they have uncovered the full facts of the case. They fear that both mother and stepfather may have systematically mistreated Typhaine. For the time being, the couple have been accused of "mistreatment causing accidental death". A postmortem examination on the child's body will attempt to decide whether her injuries point to something more deliberate.